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I have two solar panels, one is rated as $I=2A$ (current) and $V=20V$ (voltage) and the other as $I=3A$ and $V=15V$. If I connect them in parallel, how to calculate the current and voltage of the parallel connected system?

What about if I arrange them as a series circuit?

Thank you for any help!

P.S. Please let me know if you need more information or clarification

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Like all steady state circuit analysis things in parallel share the same voltage, and things in series share the same current. The question then really boils down to what the current vs. voltage curve looks like for a solar panel.

A quick search turned up this: Solar Panel I-V curve from https://www.folsomlabs.com/modeling/module/module_model

So in this case it looks like you could approximate this type of curve as constant current until the voltage requirement is met and then constant voltage.

In that case, in series they would conduct the lower of the two current limits, each at their voltage limits so $I=2A$ $V=35V$

In parallel they would would be at the lower of the two voltage limits and their currents would sum: $I=5A$ $V=15V$

Note that the power output of either of these combined circuits is less than the sum of the potential power output of the individual panels. This can actually have a dramatic effect in real solar panel arrays as the current limit is proportional to the amount of light received so if there are many panels connected in series, only one of which is shaded the output would be the same as if all of the panels were shaded.

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